AN abandoned coal mine tunnel. (image: image64.webshots.com)

Mine shafts that are about to be closed because of insufficient coal yield could be used to extract geothermal energy from the ground, write two engineers in the journal Renewable Energy, Science Daily reported on Monday.

This energy, from the internal heat of the Earth, could be used to provide electricity and hot water to nearby towns.

Converting mineshafts into geothermal boilers is an excellent way of making use of low-intensity geothermal energy, wrote Spanish engineer Rafael Rodriguez, from the Oviedo Higher Technical School of Mining Engineering. Currently, geothermal energy is rarely used in Spain.

Rodriguez and his colleague, Maria Belarmina Diaz, developed a method to determine the amount of heat a recently closed mine tunnel could provide based on earlier information, when the tunnel was in use. He explained that when the mine is still active and the tunnels accessible, one can gather data about ventilation, the properties of rocks, as well as taking samples. It is also possible to design better circuits and program the closure of certain sections of the mine to be used for geothermal energy production.
Rodriguez stressed, however, that although geothermal energy can be utilized once the mine is no longer active, it is not possible to make any changes or gather data to improve the system.

Geothermal energy is not dependent upon climatic conditions—such as solar or wind—and helps to reduce CO2 emissions. It also makes use of a local natural resource and does not pollute the surrounding area.

Although it is too soon to tell, this technology could provide much-needed energy savings to coal mining communities in the US as the coal industry continues to shrink and shed jobs.